Johan Brissmyr
CEO & Co-founder at Castle
New York, New York, United States
Summary
👤
Senior🎓
Top SchoolJohan Brissmyr is a seasoned founder and engineering leader with 16 years of experience building secure, user-focused products and teams from embedded firmware to SaaS. As CEO and co-founder of Castle he specializes in protecting consumer-facing services from bots, account takeovers, and abusive behavior while balancing security with good design and usability. Prior ventures include authentication-as-a-service and a portable digital identity startup that applied machine learning to risk scoring, reflecting a consistent focus on trust, fraud prevention, and practical threat detection. He combines low-level systems expertise from early roles in embedded imaging and video codec platforms with product-led leadership and a track record of bootstrapping companies. Based in New York, he pairs hands-on technical judgment with an eye for usable security solutions that scale.
16 years of coding experience
9 years of employment as a software developer
Master of Science (M.Sc.) Computer Science, Master of Science (M.Sc.) Computer Science at The Faculty of Engineering at Lund University
Swedish, English, German
Stackoverflow
826reputation
190kreached
2answers
0questions
javascript
top-5%
jquery
top-5%
Github Skills (49)
fraud-prevention10
ruby10
fraud-detection10
neo4j10
one-time-password10
sdk10
castle10
directed-acyclic-graph9
graph-database9
login-system9
javascript9
java9
jquery9
administrate9
graph9
Programming languages (10)
Github contributions (5)
castle/devise_castle
Apr 2014 - Mar 2018
Castle monitors your login system and stops account hijacks in real-time.
Contributions:118 commits, 1 PR, 14 pushes in 3 years 10 months
login-system
castle/playground
Mar 2016 - Feb 2018
Example implementation of Castle
Contributions:1 PR, 10 pushes, 1 branch in 1 year 11 months
castle
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